Downsampling - Why is Dec 2010 different?

As you'll recall from my previous post (and references therein...), the 2005 Orion data shows a discrepancy between ds1 and ds5 data in which the ds1 data is significantly (~10%) higher than the ds5 data. However, the 2010 Uranus observations show much larger discrepancies between ds1 and ds5 favoring the ds5 data! Because that was somewhat unbelievable to me, I ran ds1-ds5 comparisons on Uranus data from other epochs, and discovered that ds1>ds5 uniformly (also, it looks a LOT better).

So, the question remains, WHY is the Dec 2010 data brighter in ds5? More confusing to me, why do the ds5 PSFs from 2010 look so reasonable, while the ds5 PSFs from all earlier epochs look terrible?

For example, I use the observations 070727_o31 and _o32. These show clearly the blurring and flux-loss that happens when ds5 data are used for 'normal' point-sources. The disagreement is, surprisingly, worse for the co-added image, though the correlation is better... I'm not entirely clear what that means besides there being a positional offset between the individual maps that is not entirely believable.

However, the point is that these maps do not share the properties of the 2010 maps, in which the ds5 source is brighter and possibly even more peaked than the ds1 source, despite the ds1 data having lower noise (as you'd expect):

What could be boosting the flux in the Dec 2010 downsampled data? Is there something about the lines - before downsampling - that is changing the relative scaling? Perhaps I can answer this with the w5 maps... but I think that's unlikely...